New Zealand · metal roofing

Will this longrun roof work, and what do I order?

A CoP-aware takeoff for NZ metal roofs. Not another 6/12 pitch widget, and not a satellite quote machine.

Job name

Profile NZS 3604 wind zone Override cover width (mm, blank = library) Sheet length cap (m, optional) Waste override (%, blank = auto)

Standard 16.5 mm corrugate. CoP min cladding pitch 8°. Check drainage after 15 m of run.

Section name

Form Plan length (m along ridge) Eave-to-eave span (m) Pitch (degrees) Eave overhang (m) Barge / verge overhang (m) Valley count

Supplier pricebook (optional)

Sheet $/lm Ridge $/lm Barge $/lm Valley $/lm Underlay $/m²

Your rates, GST exclusive. Totals add 15% GST. Hip flashing uses the ridge rate.

Takeoff

CoP gates passed

Sloped area: 111.49 m²
Sheets: 32 @ 4.65 m
Cover: 762 mm · 15°
Waste: 5% → 117.06 m²
Ridge / hip: 12.10 / 0.00 lm
Barge / valley: 18.43 / 0.00 lm
Flashing cover: Cat A · ridge 130 mm · barge 75 mm

Dimond Corrugate sheetsCover 762 mm · length 4.65 m (rounded up 50 mm from 4.607 m) 32 sheets
Sheet lineal metres 147.43 lm
Underlay (10% lap allowance) 122.70 m²
Ridge flashing (130 mm cover) 12.10 lm
Barge flashing (75 mm profiled cover)2 upstands (CoP corrugate Cat A) 18.45 lm

Cladding pitch is not design pitch

NZMRM CoP 7.1.1A: tabulated minimums are roof cladding pitch, not the building-design roof pitch. Wide purlin or portal spacing can leave the as-laid pitch below the table even when the drawings say otherwise.

This is a takeoff, not a quote

Numbers assume rectangular planes, constant pitch, sheets laid ridge-to-eave, and published nominal cover widths. Hips, valleys, penetrations, stop-ends, and end laps change the order. Confirm on the current product sheet and the latest CoP at metalroofing.org.nz.

Most roof calculators stop at trigonometry. This one starts after you already know the pitch. Enter plan length, width, overhangs and a real NZ profile. You get sloped area, sheet count from cover width (not overall sheet width), sheet lengths, ridge, barge, hip and valley allowances, waste that changes with hips and valleys, and the warnings that actually change an order: minimum cladding pitch, CoP run-length checks, Extra High flashing cover.

The engine is shared across every tool page on this site. A garage corrugate job and a low-pitch trapezoidal house run the same numbers. Add a second section when the garage or porch is a different pitch — that is how NZ houses are actually built.

This is not a substitute for the NZMRM Code of Practice, a manufacturer data sheet, or a Licensed Building Practitioner. It is a fast independent takeoff you can screenshot and send to a merchant, with assumptions written in plain language.

FAQ

Is this a quote?

No. It is a material takeoff with CoP warnings. Labour, scaffold, removal, penetrations and access are out of scope unless you type your own rates into the optional pricebook.

Why not just use a pitch calculator?

Pitch in degrees is a 30-second calculation. The expensive mistakes are ordering corrugate at 6°, using overall sheet width instead of cover, applying a flat 10% waste to a hip roof, and missing Extra High barge cover.